The physiology of the prefrontal cortex (PFC) has been the focus of schizophrenia research for many reasons. First, using imaging techniques, a decrease in the level of activity in the prefrontal cortex of schizophrenic patients has been reported. Second, classical antipsychotic drugs have been shown to be dopamine receptor antagonists. Finally, the catecholaminergic innervation of the PFC has been shown to be extensive. These observations have lent the question of "How does dopamine modulate neuronal activity?" considerable import. Numerous studies have attempted to investigate the effects of dopamine on PFC activity using whole animal in vivo preparations, in vitro brain slice preparations, and even cell cultures. The results of such studies have been controversial. Dopamine has been shown to have excitatory, inhibitory, or even no effect at all. This confusion indicates that the questions being addressed must be more specific. We have decided to characterize the local, excitatory, synaptic connections between the primary cortical cells, the pyramidal cells. We have selected the in vitro, rat medial PFC slice preparation for these studies to allow for greater control of the extracellular environment. Once I have isolated and clearly defined a monosynaptic cortical connection, I will then evaluate the effects of exogenous dopamine application on this synaptic connection.